REAR AXLE ID.

[Tech 1]

I was just checking my Data Plate on the door of my 1970 F-100. All the numbers match up according to the Vin Decoding chart on this site except for the rear axle code. I have a rear axle code of 17. Does anyone have any information on this. I have the light duty 3 speed trans in it, but when I take off or start to back up it chatters. I suspect I may have an rear gear for an automatic in it. Note: all cab mounts, clutch and U joints are new as well as trans and motor mounts.
I think I might have just answered my own question. I looked at the 71 Data and a 17 axle code there is for a 3:25 Gear.

[FORDification]

What chatters? The 3-spd or the rearend?

[Tech 1]

Keith it chatters just like if the clutch is bad. Once the clutch is fully engaged it's ok. I just finished the restore on the truck and this was a problem I had with it before I started the restore. I thought the cab mounts might have been causing it but now they are new, and it has a new Zoom clutch in it and the flywheel was resurfased. The trans works great and it and the rear have no noise in them.